Women who take antidepressants early in pregnancy are not at a higher risk of having children who develop autism or attention deficit hyperactivity disorder (ADHD), contrary to earlier reports, a study published Tuesday found.
The new study, published in the Journal of the American Medical Association, found only a slight increase in the risk of premature birth for infants of mothers who used antidepressants during the first trimester of their pregnancy. But the researchers found no increase in the risk of autism, ADHD or reduced fetal growth among children exposed to antidepressants during fetal development.
One strength of the study is that it included siblings from the same mothers, comparing children who were exposed to antidepressants during pregnancy with their brothers or sisters who were not. Those children grew up in similar environments and had similar genes, which would make it more likely that the effect of antidepressants during pregnancy would stand out.
The study, conducted in collaboration with researchers at Harvard T.H. Chan School of Public Health and at Karolinska Institute in Sweden, analyzed data on all live births in Sweden from 1996 to 2012. Data about the country's antidepressant prescriptions in adults, autism and ADHD diagnoses in children, parents' age and education levels, genetic relationships between parents and children and other characteristics were also incorporated in the study, which allowed researchers to control for other risk factors for developmental disorders.
Researchers were able to study a very large population sample, about 950,000 mothers and about 1.6 million children, which enabled them to look at rare outcomes. And researchers were able to get measures of antidepressant use based both on mothers' self-report and when they were given the medications from a pharmacy. The study controlled for a number of factors to isolate the effects of medication.
"The fact that we got consistent answers when we used all of these designs gives us more confidence in our conclusion," said Brian D’Onofrio, senior author of the study and professor at Indiana University.
A majority of the antidepressants examined in the study were selective serotonin re-uptake inhibitors, more commonly known as SSRIs, which are the most common type of antidepressants. Prozac, Celexa and Zoloft are a few of these commonly used SSRIs.
The study also looked at antidepressant use in fathers, as well as mothers' use of antidepressants before but not during pregnancy. All of these uses were found to be associated with increased risk for autism, ADHD and poor fetal growth. This provides evidence that environmental and family factors influence the likelihood of offspring developing these conditions.
"What this did was help us have a measure of the likelihood of either parent having depression and whether that likelihood is associated with the outcome, and of course we found that," D'Onofrio said. "So this provides more evidence that it is not the medication during pregnancy, but factors associated with either parent having depression, like genetics, for example."